To tell the truth, these are a bit of a disappointment. They aren’t really loud enough, for my taste. But, they are the genuine item, and there weren’t very many of them, so here they are.
Unlike old-style bike bells, this doesn’t have a thumb-striker. On these, you just give the housing a quick twirl. Made of durable, black plastic. 2.25”Ø x 1.5”